Validating NestJS DTOs

When to use

• Adding or refactoring DTOs
• Hardening boundary input
• Removing manual validation from controllers

Core rules

1. Global ValidationPipe with whitelist: true, forbidNonWhitelisted: true
2. DTOs use class-validator decorators: @IsEmail(), @IsString(), @MinLength()
3. Use @Type() from class-transformer for type conversion
4. No manual validation in controllers
5. DTOs in application/dtos/ folder

Reference shape (TypeScript)